In short, because your truck is essentially stock.

 

Me too!

I bought my HPTuners about 6 years ago for $200, to tune my old 2000 Camaro SS. Car is long gone, but I "tinker" with my truck just to try and stay somewhat current with how to use it.

 

you should really try to rent a dyno out and try it, 12.8 AFR really dont mean you tuned for best performance my 87 truck like 12.6ish ARF got max power there my 2k z28 loved 11.4 / 11.6 AFR, my z28 made 350rwhp with a AFR in mid 12's but at mid 11's made 380rwhp

i think its really cool you guys are doing your own tuning I just dont get it I've tried to mess with my 87 since its the holley injection i have the program on my laptop but just goof it up and reload the dyno tune lol

 

Stock tune is way off from the numbers I got, but I am sure you know that.

As already mentioned in post#4, I tuned my old Mustang using narrow bands with great results, so the "because its stock" theory is kind of a moot point in my experience. That was a Vortech YS trimmed car fwiw.

I also narrow band tuned my 2000 Camaro SS which had cam, converter and all the bolt-ons/free mods. When a local LS tuning expert dyno tuned the car it ran a best of 11.87@113 and all around drivability sucked.
Narrow band tuning it using time slips and O2 voltage readings got me a best of 11.61@116, and over 200 passes in the 11.60's, so the moral of the story is that it can absolutely be done successfully...

 

I'm definitely not that concerned to justify a $400 dyno session. I've driven my truck now for almost 6 years and am confident its running its best all around. Its a truck that is used as a work truck and actually tows and hauls, but has still whooped its fair share of trucks (and cars). Nothing more fun than pulling alongside one of those clowns with smokestacks and pimp slapping them with a little quiet 5.3.

 

I love a fast truck, if you beat a car with a car oh well but if you beat a car with a truck they'll never forget it

as for the $400 dyno for me I'm not a self tuner so it make sense for me to do it, if i did my own tuning i'd do it at the track.......either way its cool to self tune..

 

Are these results with the fuel trims turned off??

 

Yes. My LTFT's have been turned off for two years or more.